How does s2Member deal with spam?
Taking Measures to Prevent Spam Bots from Registering
If you plan to allow Open Registration, this is extremely important. Spam bots surf the Internet every minute of every day—just looking for ways to create free accounts and/or spoof their identity. If you open your site to Free Registration (of any sort), you can expect to find lots of this; unless you are wise & take the proper precautions.
s2Member Pro-Forms come pre-integrated with Google's reCAPTCHA service. For Free Registration Pro-Forms, this is enabled by default. reCAPTCHA is a free service to protect your website from spam and abuse. reCAPTCHA uses an advanced risk analysis engine and adaptive CAPTCHAs to keep automated software from engaging in abusive activities on your site. It does this while letting your valid users pass through with ease.
See: s2Member Pro-Forms for more information.